…r#8314)

Reverts flutter#6749

This is failing the publish step:

```
Running 'build_and_copy' in shared_preferences_tool
[build_and_copy] Building the extension Flutter web app...
Could not find an option named "--web-renderer".

Run 'flutter -h' (or 'flutter <command> -h') for available flutter commands and options.
Unhandled exception:
ProcessException: Failed with exit code: 64
  Command: flutter build web --web-renderer canvaskit --pwa-strategy=offline-first --release --no-tree-shake-icons
#0      BuildExtensionCommand._runProcess (file:///b/s/w/ir/x/w/.pub-cache/hosted/pub.dev/devtools_extensions-0.2.2/bin/_build_and_copy.dart:134:7)
<asynchronous suspension>
#1      BuildExtensionCommand.run (file:///b/s/w/ir/x/w/.pub-cache/hosted/pub.dev/devtools_extensions-0.2.2/bin/_build_and_copy.dart:57:5)
<asynchronous suspension>
flutter#2      CommandRunner.runCommand (package:args/command_runner.dart:212:13)
<asynchronous suspension>
flutter#3      SharedStdIn.terminate (package:io/src/shared_stdin.dart:91:3)
<asynchronous suspension>
flutter#4      main (file:///b/s/w/ir/x/w/.pub-cache/hosted/pub.dev/devtools_extensions-0.2.2/bin/devtools_extensions.dart:16:3)
<asynchronous suspension>
```